1. Technical Field
The present disclosure relates to semiconductor memory devices and methods of forming the same, and more particularly, to variable resistance memory devices and methods of forming variable resistance memory devices.
2. Discussion of Related Art
A high read/write operation speed, nonvolatility and a low operation voltage enhance the performance of memory devices such as static random access memories (SRAM), dynamic random access memories (DRAM) and flash memories.
A unit cell of the DRAM includes one capacitor and one transistor controlling the capacitor. A unit cell of the SRAM includes six transistors. Thus, each of the unit cells of the DRAM and SRAM is larger as compared with a unit cell of a NAND flash memory. Both the DRAM and the SRAM perform a refresh operation, which is not required in the NAND flash memory, but are capable of faster operation than NAND flash memory.
A phase change random access memory (PRAM) has a high read/write operation speed, nonvolatility and a low operation voltage as compared to the DRAM, SRAM and NAND flash memory.